The invention relates to a dowel setting device for use with a formless paving machine, where a plurality of booms in the form of dowel retrievers are disposed ahead of the devices for compacting the concrete, where the dowel retrievers retrieve dowels from a magazine and extend, looking in the direction of travel, from the front into the area of beginning compacting of the concrete parallel to the direction of travel and eject the dowel there.
A dowel setting device of this type is known from DE-OS 22 59 040. Although this dowel setting device is distinguished by a comparatively simple structure, this must be paid for with a disadvantage which in actuality cannot be disregarded. In accordance with FIG. 1 in the drawings of this pre-publication, the support 10 of this dowel setting device is continuously being pushed through the loose concrete piled up in front of the formless paving machine. As a result it yields laterally and it is necessary to return it, in a manner not described into the space between the support of the dowel setting device and the guide plate 11 of the formless paving machine. This support 10 furthermore hampers the discharge of concrete ahead of the formless paving machine, i.e. it is not possible to dump the concrete directly in front of the guide plate or the like of the formless paving machine.
As is known, the formless paving machine produces concrete surfaces such as streets, concrete roads and the like in a continuous movement. Liquid concrete, i.e., concrete that has not yet hardened, is loosely piled in front of the machine from trucks. It is then distributed by a distributor screw, which is disposed crosswise to the direction of travel, and is subsequently compacted and smoothed by a vibrator and a pressure tamper following it. Then the dowel setting device places dowels into the not yet hardened concrete at preset distances in rows parallel to the direction of travel. After the concrete has set a little, grooves are cut at this place crosswise to the dowels. Upon further hardening of the concrete, the concrete cover breaks at these places. Because of this, individual concrete slabs are created which are separated from each other but fixed in relation to each other by the previously pressed-in dowels. The dowels prevent the offset of these these concrete slabs from each other in height and form barriers.
If, instead of inserting the dowels behind the formless paving machine, they are inserted into the not yet hardened concrete ahead of the formless paving machine in accordance with the previously known dowel setting device, an advantage is achieved that in this case the concrete has not yet hardened 100% and the surface has not been finally smoothed. Thus, dowel setting does not require any after-treatment of the concrete surface the way it does with dowel setting devices which are disposed, looking in the direction of travel, behind the formless paving machine.
Dowel setting devices disposed behind the formless paving machine do have the advantage that they do not hamper the dumping of the concrete ahead of the formless paving machine. However, as stated before, they require extensive after-treatment.